Green roofs are being studied as a means to increase vegetation and preserve aesthetics in old Mediterranean cities. In order to preserve ancient cities' local character and biodiversity, researchers are looking to native plant species that can withstand the low water environments that are necessary in lightweight green roof design.
Xerophytes--species of plants that have adapted to survive in environments with little water--fit well in green roof construction plans, creating lightweight roofs that don't compromise ancient buildings' structural concerns.
A research team in Athens explored the use of three Mediterranean aromatic xerophytes, Artemisia absinthium, Helichrysumitalicum, and H. orientale, for use in an extensive green roof design. The study, published in HortScience, also investigated the practice of using of locally produced grape marc compost to promote drought resistance, and looked at the effects of different planting depths and irrigation frequencies on the three aromatics.
According to the Maria Papafotiou from the Department of Crop Science at the Agricultural University of Athens, most Mediterranean cities are centered around their old nucleus, which in many cases is characterized as a historical heritage. "These cities lack areas that could be converted into conventional green spaces, and thus there is an increasing interest in green roof systems. Green roofs are still relatively uncommon in Mediterranean countries, although these areas would significantly benefit from the ecological and technical functions of this technology," Papafotiou explained.
The scientists planted rooted cuttings of the three aromatics in a green roof infrastructure they then placed on a fully exposed flat roof in Athens. Two types of substrates were used (grape marc compost:soil:perlite and peat:soil:perlite ) at two substrate depths, 7.5 cm (shallow) and 15 cm (deep). The team applied two irrigation frequencies throughout the study: sparse (5 or 7 days in shallow and deep substrate, respectively) and normal (3 or 5 days in shallow and deep substrate, respectively), and recorded plant growth from May to October.
Results showed that all three of the plant species were established successfully on the green roof under all experimental treatments, although Artemisia absinthium generally showed the greatest growth as indicated by the final diameter and height of the plants. "With A. absinthium, grape marc compost-amended substrate produced taller plants and larger plant diameter compared with peat-amended substrate, deep substrate produced larger plant diameter compared with shallow substrate, and normal irrigation produced taller plants compared with sparse irrigation," the researchers said. "In both Helichrysum species, we found there were interactions of the main factors in almost all growth parameters; therefore, the only conclusion we drew concerning factor effects was that irrigation frequency did not affect the diameter and the dry weight of H. italicum plants."
The researchers noted that a "remarkable result" was that shallow compost-amended substrate with sparse irrigation resulted in similar or even bigger plant growth of all plant species compared with deep peat-amended substrate with normal irrigation.
"We determined that all three aromatic species were suitable for use in Mediterranean extensive or semi-intensive green roofs, and additionally found that the use of grape marc compost in the substrate allowed for less water consumption and the reduction of substrate depth without restriction of plant growth at the establishment phase and the first period of drought," Papafotiou said.
The complete study and abstract are available on the ASHS HortScience electronic journal web site: http://hortsci.ashspublications.org/content/48/10/1327.abstract
Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application.
Mike W. Neff | EurekAlert!
Covering the bases with cover crops
01.10.2015 | American Society of Agronomy
Innovative seeding machine to speed up kenaf planting
23.09.2015 | Universiti Putra Malaysia (UPM)
The MICADO camera, a first light instrument for the European Extremely Large Telescope (E-ELT), has entered a new phase in the project: by agreeing to a Memorandum of Understanding, the partners in Germany, France, the Netherlands, Austria, and Italy, have all confirmed their participation. Following this milestone, the project's transition into its preliminary design phase was approved at a kick-off meeting held in Vienna. Two weeks earlier, on September 18, the consortium and the European Southern Observatory (ESO), which is building the telescope, have signed the corresponding collaboration agreement.
As the first dedicated camera for the E-ELT, MICADO will equip the giant telescope with a capability for diffraction-limited imaging at near-infrared...
Self-driving cars will be on our streets in the foreseeable future. In Graz, research is currently dedicated to an innovative driver assistance system that takes over control if there is a danger of collision. It was nature that inspired Dr Manfred Hartbauer from the Institute of Zoology at the University of Graz: in dangerous traffic situations, migratory locusts react around ten times faster than humans. Working together with an interdisciplinary team, Hartbauer is investigating an affordable collision detector that is equipped with artificial locust eyes and can recognise potential crashes in time, during both day and night.
Inspired by insects
An interdisciplinary team of researchers has built the first prototype of a miniature particle accelerator that uses terahertz radiation instead of radio...
At present, tiny magnetic whirls – so called skyrmions – are discussed as promising candidates for bits in future robust and compact data storage devices. At...
In cooperation with the Center for Nano-Optics of Georgia State University in Atlanta (USA), scientists of the Laboratory for Attosecond Physics of the Max Planck Institute of Quantum Optics and the Ludwig-Maximilians-Universität have made simulations of the processes that happen when a layer of carbon atoms is irradiated with strong laser light.
Electrons hit by strong laser pulses change their location on ultrashort timescales, i.e. within a couple of attoseconds (1 as = 10 to the minus 18 sec). In...
01.10.2015 | Event News
30.09.2015 | Event News
17.09.2015 | Event News
08.10.2015 | Earth Sciences
08.10.2015 | Information Technology
08.10.2015 | Physics and Astronomy